Membranes can be used for various purposes in irrigation drip emitters in connection to waterways formed in the emitter. For example, a membrane may be used for controlling the flow rate of water discharged by the emitter, for sealing between parts of the emitter, for defining valves in the emitter and/or for defining flow-paths within the emitter.
In control of flow rate, for example, the membrane operates to control liquid flow out of the emitter so that it is substantially independent of pressure at an inlet of the emitter for a range of pressures typically encountered in irrigation applications. For this purpose, the membrane is normally located between inlet and outlet waterways of the emitter and in response to increase in pressure of the entering water undergoes distortion that operates to increase resistance to liquid flow through and out of the emitter.
U.S. Pat. No. 4,210,287 discloses an emitter unit provided with a resiliently flexible membrane, which is releasably retained within a body member so as to serve a double function. On the one hand, whilst being exposed to the irrigation flow pressure in the conduit to serve in exercising differential pressure control, and, on the other hand, to define, with respect to a flow restricting waterway groove formed in the body member, a flow-restricting waterway flow-path.
Provision of drip emitters that are less expensive is desirable and one way of providing same may be to design a drip emitter from a single part, which thus requires less of substantially no assembly steps to be completed for use. In particular, provision of such a single part drip emitter may be beneficial in drip emitters that are made from different type materials, such as pressure regulated drip emitters that typically include a plastic body and an elastic membrane for assisting in the pressure regulation.